Royal & SunAlliance (R&SA) is facing a £14m claim after the National Motorcycle Museum in Solihull was gutted by fire.
As well as substantial damage to the museum building, around two-thirds of its rare exhibits were destroyed.
R&SA, which insures the museum through Midlands broker Perkins Slade, has instructed loss adjuster Crawford to investigate the damage.
A National Motorcycle Museum statement said: "Sadly, three of the museum's five exhibit halls have been destroyed along with their exhibits, probably totalling around 500 machines."
The museum said its largest suite is being refurbished after smoke and water damage, but is expected to reopen for "larger events" on 1 January 2004.
R&SA was unable to confirm the cost of the damage, but sources estimate the lost exhibits were worth around £9m, while replacing the building would cost another £5m.